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vbk22398
Senior
Apr 30, 2025 6:41 AM UTC
Question

RED LED On due to unknown reason!

I am using STM32F767ZI board for my projects. But due to some unknown reason, the RED led is turned ON in my nucleo board. I am sharing my code along. The code is very simple and I enabled only a single GPIO to be output. Please let me know my mistake! Where am I going wrong. What is my issue.! Also i haven't enable any GPIO that concerns RED Led. Please let me know the answer!

Thanks! 

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7 replies

Andrew Neil
Super User
Apr 30, 2025 7:08 AM UTC

@vbk22398 wrote:

I am using STM32F767ZI board for my projects.  


Do you mean the NUCLEO-F767ZI ?
https://www.st.com/en/evaluation-tools/nucleo-f767zi.html


@vbk22398 wrote:

 the RED led is turned ON  


You mean LD3 ?

AndrewNeil_0-1745996819662.png

 


@vbk22398 wrote:

due to some unknown reason,  


Have you tried stepping through your code in the debugger to see exactly when it comes on?

 

PS:

You can download the schematics from the 'CAD Resources' Tab on the board's Product Page:

https://www.st.com/en/evaluation-tools/nucleo-f767zi.html#cad-resources

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
LCE
Principal III
Apr 30, 2025 7:19 AM UTC

Which LED do you mean?
Several LEDs on the Nucleo, and some connected to the on-board ST-Link, some at the power supplies...

Andrew Neil
Super User
Apr 30, 2025 7:42 AM UTC

@LCE wrote:

Several LEDs on the Nucleo, and some connected to the on-board ST-Link, some at the power supplies...


Indeed.

@vbk22398 here's the full list:

 

AndrewNeil_1-1745998751545.png

AndrewNeil_2-1745998763482.png

So there's four LEDs which could possibly show red ...

AndrewNeil_3-1745998919618.png

 

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
vbk22398
vbk22398Author
Senior
Apr 30, 2025 12:10 PM UTC

LD3.

vbk22398
vbk22398Author
Senior
Apr 30, 2025 12:11 PM UTC

@Andrew Neil I tried to enter into debug mode but it doesn't start from main, it starts outside main and if i go inside the function, then it opening a function inside the main, whilst the debug is still outside in some random line.!

Tesla DeLorean
Guru
Apr 30, 2025 12:19 PM UTC

Like it ended up in Error_Handler?

Or it's just running some completely different code? Double check build completes and you download correctly. 

Perhaps mass erase and confirm LED goes off.

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